In recent years, together with the advancement of miniaturization and reduction in weight of electronic apparatus such as image pickup apparatus represented by a digital camera and so forth, a battery installed in an electronic apparatus is formed in a parallelepiped shape advantageous for miniaturization and reduction in weight. Meanwhile, it is necessary for an electronic apparatus to which a battery is applied to be formed from a member having rigidity sufficient to withstand a bending moment in order to prevent erroneous insertion of the battery or prevent damage to an image pickup apparatus, and this makes an obstacle to miniaturization and reduction in weight.
Therefore, as shown in FIG. 28, a battery 9 disclosed in Japanese Patent Laid-Open No 2003-317689 is formed in a parallelepiped shape wherein the length of the sides in an insertion direction is set longer than the length of the sides in the widthwise direction in order to prevent erroneous insertion into an electronic apparatus while cutaway portions 91 are formed on the sides of a sheath member 90 of the battery 9 to prevent erroneous insertion with certainty and besides facilitate miniaturization and reduction in weight of the electronic apparatus into which the battery 9 is to be installed. The sheath member 90 has terminals 92 provided thereon for electrically connecting to terminals of the electronic apparatus into which the battery 9 is to be installed. The number and location of the cutaway portions 91 are determined so that an end face 93 does not have the center of symmetry. Meanwhile, a battery holder in the electronic apparatus in which the battery 9 is accommodated has an internal shape substantially same as an outer shape of the sheath member 90 and has protrusions for engaging with the cutaway portions 91 when the battery holder is accommodated. It is to be noted that, as batteries similar to the battery disclosed in Japanese Patent Laid-Open No. 2003-317689, batteries disclosed in Japanese Patent Laid-Open No. Hei 11-307072, Japanese Patent Laid-Open No. 2001-76700 and Japanese Patent Laid-Open No. Hei 11-3692 are available.
The battery 9 is charged up suitably by a charging apparatus. As the charging apparatus, a charging apparatus disclosed, for example, in Japanese Patent No. 2,508,447 is applicable. The charging apparatus mentioned includes an installation section in which the battery 9 is removably installed. The installation section has terminals provided thereon for electrically connecting to the terminals 92 of the battery 9.